Crucial Role of Water in the Mechanosynthesis of CsPbI3 and Other ABX3 Halides

Mechanochemical synthesis of CsPbI₃, as a model system for ABX₃ halides, was studied. Water was shown to strongly promote the kinetics of formation of CsPbI₃ from the CsI+PbI₂ mixture through increased mobility of the constituting ionic species. Since many binary and ternary halides are hygroscopic, it was concluded that the presence of small, uncontrollable and unintentional additions of water should often occur in both precursor mixtures and synthesized complex halides boosting the kinetics of formation of many, if not all, ternary organic–inorganic hybrid halides such as, for example, MAPbX₃ (X=Cl, Br, I). In addition, trace amounts of water should influence the transport characteristics of complex halides. Thus, the presence of water explains, at least partially, the huge scatter in both the reported mechanochemical reaction times necessary for obtaining single-phase APbX₃ perovskite halides and the activation energies of ionic diffusion in APbX₃.     

Statistical models in sounding problems

Scientific-Research Institute of Mechanics, Gor'kii University. Translated from Izvestiya Vysshikh Uchenykh Zavedenii, Radiofizika, Vol. 32, No. 12, pp. 1502–1505, December, 1989.     

Stabilization of water/n‐hexane emulsions by amphiphilic copolymers based on vinyl ethers and their polycomplexes with poly(acrylic acid)

Amphiphilic random copolymers based on vinyl ether of ethylene glycol and vinyl butyl ether as well as their polycomplexes with poly(acrylic acid) were studied as polymeric reagents for the stabilization of water/n‐hexane emulsions. The emulsion stability strongly depended on the content of vinyl butyl ether in the copolymers as well as their concentration in solution. The more hydrophobic copolymers stabilized emulsions more efficiently. An increase in the temperature and the addition of inorganic salts reduced the emulsion lifetime. The formation of interpolymer complexes between the copolymers and poly(acrylic acid) significantly influenced the stability of the emulsions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2625–2632, 2004     

Crytal and molecular structure of hydrido(trichlorostannyl)bis-cyclopentadienyl molybdenum(η5-C5H5)2Mo(H)SnCl3

On the basis of X-ray analysis the crystal and molecular structures of (η₅-C₅H₅)₂Mo(H)SnCl₃ have been determined. The compound crystallizes in the monoclinic system with parameters: a = 8.313(3), b = 13.109(4), c = 6.384(2) Å, β = 106.52(2)°, space group P2₁/m, R = 0.028. The conformation occurring in Cp₂Mo(H)SnCl₃ is that with the maximum repulsion between the chloride atoms and the cyclopentadienyl rings. The hydride H atom is shielded by the cyclopentadienyl groups and chlorine atoms, which accounts for the compound's stability to oxygen and hydrolysis.     

Analysis of Adsorption Isotherms: Lattice Theory Predictions, Classification of Isotherms for Gas–Solid Equilibria, and Similarities in Gas and Liquid Adsorption Behavior

Adsorption at fluid–solid interfaces is considered in the framework of a lattice with boundaries. Using ideas proposed by S. Ono and S. Kondo (in“Molecular Theory of Surface Tension in Liquids” (S. Flügge, Ed.), Encyclopedia of Physics, Vol. 10, p. 134. Springer-Verlag, Berlin, 1960), a lattice model is derived, both rigorously and phenomenologically, and applied to macro-, meso-, and microporous adsorbents by imposing different boundary conditions. It is shown that this lattice theory can predict the entire spectrum of behavior observed when gases, liquids, or supercritical fluids adsorb on solid surfaces. In particular, it is able to predict steps in the isotherms, scaling behavior near saturation conditions, supercritical behavior, and adsorption hysteresis. It is shown that there is a profound analogy in the adsorption behavior of a one-component gas to that of a binary liquid mixture. This analysis leads to a new classification of physisorption isotherms for fluid/solid equilibria.     

Specific feature of synthesis and technological scheme for manufacture of nonstoichiometric hydroxo chromium(III) formates

Specific features of the hydrothermal interaction between chromium(VI) oxide and formic acid to give water-soluble nonstoichiometric hydroxo chromium(III) formates with compositions from the range Cr(OH)_0.66(HCOO)_2.34-Cr(OH)_1.55(HCOO)_1.45 were studied. These compounds can be used in formulations for chromium-plating electrolytes and tanning agents.     

Adsorption of Supercritical Fluids

Adsorption isotherms for supercritical fluids are calculated using lattice theory. Results are compared with experimental data for methane on graphon and for carbon dioxide on coal. It is shown that the model reflects the peculiar features in adsorption isotherms of supercritical fluids (in particular, a maximum in the adsorption with increasing pressure). The analysis shows that there is two layer adsorption over a wide range of densities.     

Crystal structure of lanthanum potassium octacyanomolybdate(IV) nonahydrate

The crystal structure of KLaMo(CN)₈ · 9H₂O was determined from X-ray diffraction data. The crystals are monoclinic, space group P2₁/c, a = 8.7451(4), b = 25.2761(13), c = 10.6744(5) Å, β = 117.059(3)°, V = 2101.22(17) ų, Z = 4, ρ(calcd) = 2.037 g/cm³, R = 0.0242, wR ₂ = 0.0500 for 5656 independent reflections. The coordination polyhedra of the Mo, La, and K atoms are the tetragonal antiprism [Mo(CN)₈], the monocapped tetragonal antiprism [La(NC)₄(OH₂)₅], and the strongly distorted monocapped trigonal prism [K(NC)₃(OH₂)₄], respectively. The La and K atoms are N-linked by seven bridging cyano groups to form double layers with two sandwiched uncoordinated water molecules and the sandwiched terminal CN group. The complex can be formulated as “[K(H₂O)₂][La(H₂O)₅][Mo(CN)₈]” _n · 2nH₂O.